The nice people from Ordnance Survey have sent me a complete set of VectorMapDistrict data (which is on 6 DVDs!). Surprisingly they didn't even charge me for the DVDs or postage.
Now I have all that data I thought I'd better do something with it!
First step was to get it onto a nice fast disk, so I copied it onto the hard disk of my server...which took a while...
Then I tried to use my vmdmap.py program to render it all, but mapnik bombed out with an error as it was adding the various shapefile layers. I suspect that this is because every single shapefile is in its own layer, as it is a completely separate datasource, and I think I either ran out of memory or hit some mapnik internal limit. This means I can't use vmdmap.py to render the whole country, which is a bit of a shame.
To get around this I think I need to merge them into a single datasource. I don't know enough about manipulating shapefiles to do this, so instead am making use of shp2pgsql which allows you to import a shapefile into a postgresql database. I have written another program, based on vmdmap.py called vmd2pgsql which will scan through a directory tree looking for the various shapefiles in the vectormap district dataset, and importing them into postgresql. This gives a much lower number of tables - just one per shapefile name, but each one will have a lot of data.
It is importing now, so will see how long the import takes, then how well it renders. I suppose it should render ok because I have the whole UK OSM dataset in a single database and that works, but we'll see over the weekend if it ever finishes! The code is at my google code site.
Showing posts with label OS OpenData. Show all posts
Showing posts with label OS OpenData. Show all posts
Friday, 1 October 2010
More Rendering of VectorMapDistrict Data
The nice people from Ordnance Survey have sent me a complete set of VectorMapDistrict data (which is on 6 DVDs!). Surprisingly they didn't even charge me for the DVDs or postage.
Now I have all that data I thought I'd better do something with it!
First step was to get it onto a nice fast disk, so I copied it onto the hard disk of my server...which took a while...
Then I tried to use my vmdmap.py program to render it all, but mapnik bombed out with an error as it was adding the various shapefile layers. I suspect that this is because every single shapefile is in its own layer, as it is a completely separate datasource, and I think I either ran out of memory or hit some mapnik internal limit. This means I can't use vmdmap.py to render the whole country, which is a bit of a shame.
To get around this I think I need to merge them into a single datasource. I don't know enough about manipulating shapefiles to do this, so instead am making use of shp2pgsql which allows you to import a shapefile into a postgresql database. I have written another program, based on vmdmap.py called vmd2pgsql which will scan through a directory tree looking for the various shapefiles in the vectormap district dataset, and importing them into postgresql. This gives a much lower number of tables - just one per shapefile name, but each one will have a lot of data.
It is importing now, so will see how long the import takes, then how well it renders. I suppose it should render ok because I have the whole UK OSM dataset in a single database and that works, but we'll see over the weekend if it ever finishes! The code is at my google code site.
Now I have all that data I thought I'd better do something with it!
First step was to get it onto a nice fast disk, so I copied it onto the hard disk of my server...which took a while...
Then I tried to use my vmdmap.py program to render it all, but mapnik bombed out with an error as it was adding the various shapefile layers. I suspect that this is because every single shapefile is in its own layer, as it is a completely separate datasource, and I think I either ran out of memory or hit some mapnik internal limit. This means I can't use vmdmap.py to render the whole country, which is a bit of a shame.
To get around this I think I need to merge them into a single datasource. I don't know enough about manipulating shapefiles to do this, so instead am making use of shp2pgsql which allows you to import a shapefile into a postgresql database. I have written another program, based on vmdmap.py called vmd2pgsql which will scan through a directory tree looking for the various shapefiles in the vectormap district dataset, and importing them into postgresql. This gives a much lower number of tables - just one per shapefile name, but each one will have a lot of data.
It is importing now, so will see how long the import takes, then how well it renders. I suppose it should render ok because I have the whole UK OSM dataset in a single database and that works, but we'll see over the weekend if it ever finishes! The code is at my google code site.
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